This Flex Mount is designed to fit Canon 580EXII units but also fits Bower SFD35, Nissin Di622, Nissin Di866, Sigma EF-430, Sigma EF-500 DG S and Sunpak 444D. Color gels may be fitted inside the Flex for creative effects. You do not need to use any glue, rubber bands or Velcro on the Flex Mounts, they stay in place when properly installed. Front mounting clips on the mount allow quick attachment of Strobies products allowing you to change from a Beauty Dish to a Snoot in seconds.